This is the .

Beneath the soil, past the roots, and beyond the reach of the sun, there is a place where light is not just absent, but impossible.

If you turned off your headlamp in the Deep Dark, you would experience . Your pupils would dilate to their maximum—9 millimeters—searching for a single wave of electromagnetic radiation. They would find nothing. You would lose the boundary between your eyelids being open or closed. The Silent Ecosystem Yet, life persists where the sun does not.